HDU 1166 敌兵布阵

树状数组

#include <cstdio>

#include <cstring>

using namespace std;

const int N=50010;

int T,n,cnt=1,x,y;

char s[6];

int c[N];

void init(){for(int i=0;i<N;i++)c[i]=0;}

void add(int x,int num){while(x<=n)c[x]+=num,x+=x&-x;}

int sum(int x){int s=0;while(x>0)s+=c[x],x-=x&-x;return s;}

int main(){

    scanf("%d",&T);

    while(T--){

        init();

        scanf("%d",&n);

        for(int i=1;i<=n;i++){scanf("%d",&x);add(i,x);}

        printf("Case %d:\n",cnt++);

        while(scanf("%s",s),strcmp(s,"End")){  

            scanf("%d%d",&x,&y);  

            if(strcmp(s,"Add")==0)add(x,y);  

            else if(strcmp(s,"Sub")==0)add(x,-y);  

            else printf("%d\n",sum(y)-sum(x-1));         

        } 

    }

    return 0;

}

线段树

#include <cstdio> 

#include <cstring>

const int N=60000;

int T,n,cnt=1,x,y,sum[N<<2];

char s[6];

void init(){for(int i=1;i<N*4;i++)sum[i]=0;}

void up(int x){sum[x]=sum[x<<1]+sum[x<<1|1];}

void build(int l,int r,int x){

    if(l==r){scanf("%d",&sum[x]);return;}

    int mid=(l+r)>>1;

    build(l,mid,x<<1); build(mid+1,r,x<<1|1);

    up(x);//注意不要漏写

}

void update(int t,int num,int l,int r,int x){

    if(l==r){sum[x]+=num;return;}

    int mid=(l+r)>>1;

    if(t<=mid)update(t,num,l,mid,x<<1);

    else update(t,num,mid+1,r,x<<1|1);

    up(x);//同上

}

int query(int L,int R,int l,int r,int x){

    if(L<=l&&r<=R){return sum[x];}

    int mid=(l+r)>>1,tmp=0;

    if(L<=mid)tmp+=query(L,R,l,mid,x<<1);

    if(R>mid)tmp+=query(L,R,mid+1,r,x<<1|1);

    return tmp;

}

int main(){

    scanf("%d",&T);

    while(T--){

        init();

        printf("Case %d:\n",cnt++);

        scanf("%d",&n);

        build(1,n,1);

        while(scanf("%s",s),strcmp(s,"End")){  

            scanf("%d%d",&x,&y);  

            if(strcmp(s,"Add")==0)update(x,y,1,n,1);  

            else if(strcmp(s,"Sub")==0)update(x,-y,1,n,1);  

            else printf("%d\n",query(x,y,1,n,1));         

        }  

    }

    return 0;

}